Deliver service API


I need my users to receive by email once they sold their item a dispatch slip ( kind link vinted) but i am not sure how to do this in Europe.

Which deliver service is the easiest one to integrate ?
UPS seems a bit difficult i red their API…

Thanks api

Hello, here’s an article that includes a list of delivery companies which have APIs : Top 10 Best Shipping API: FedEx, UPS, USPS and more | by Yasu | Rakuten RapidAPI | Medium

Thank you!

These guys offer a broker and cover all the big shippers and have an API: Parcel2Go Free Shipping API | Parcel2Go API Documentation